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Questions tagged [geotechnical-engineering]

Geotechnical Engineering is a branch of Civil Engineering focused on the engineering properties and behavior of natural and engineered geomaterials (soils and rocks), as well as the design and construction of foundations, earth dams and levees, retaining walls, embankments, underground structures ...

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What diameter of particles will result in a blocked borehole?

My mine is looking to install a 600 mm open borehole to drop particles up to 150 mm through. It's a 320m shaft to drop ballast down to save time compared to using the drift. When it gets blocked ...
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1answer
264 views

Thai Cave Rescue- Why the narrow portions are not being broadened?

Tham Luang cave rescue incident is taking combined effort of Engineers throughout the world. Various news media is telling currently it is not possible to pass more than one person through some very ...
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1answer
22 views

Liquid Limit of Soil through Atterberg Tests

My lab is evaluating the liquid, plastic, and shrinkage limits of some soil samples and we are following this video provided by the Missouri University of Science and Technology. The video indicates ...
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The use of Theis equation based on time

The storage coefficient (s) for artesian basin can be determined by the following equation (Theis equation): $$s=\frac{Q}{4\pi T}\int_{\frac{r^2S}{4Tt}}^\infty\frac{e^{-u}}{u}du$$ Does this ...
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1answer
61 views

How do you convert “kps” to Pounds per Square Foot (psf)? [closed]

I'm looking at a soil bearing capacity report, which has a column labeled "kips" and the values are followed by "kps". A "kip" is 1000 pounds, but I'm not sure how to convert from "kps" to psf. The ...
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28 views

Effect of drawdown of water

My textbook has the following question: Determine the factor of safety (in regard to cohesion only) for a submerged embankment 30.5 m (100 ft) high whose upstream face has an inclination ...
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1answer
92 views

Why is this construction site pouring gravel over a wire mesh, and then covering it with dirt?

My office is afforded a prime view of a construction project where the workers are currently covering the leveled ground in a wire mesh, raking gravel across the entire mesh, and then covering that ...
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1answer
79 views

How maps of globe, country or region were created few decades/centuries ago when modern technology like today did not exists?

What techniques were used to create the maps of a world, country or region when satellite or similar technology did not exists few decades or centuries ago?
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1answer
53 views

Are pumps used in geothermal systems

The water held underground in a geothermal system is under high temperature and pressure. Are pumps used to raise the very hot underground water to the surface or does the water rise under its own ...
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31 views

Cut in slope pore water pressure

https://imgur.com/a/YFPzR https://imgur.com/a/SgkR0 https://imgur.com/a/ZNrdR In the notes , I cant understand that why as the pore water pressure dissipated , the shear strength of soil will ...
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1answer
23 views

What types of oil reservoirs are applicable to radio/microwave heating and advantageous to SAGD?

I am doing a project looking into the advantages of radio/microwave heating of oil reservoirs. I've seen research indicating that RF/Microwave heating can be used for environments such as shallow, ...
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71 views

Is possible for a silt soil to be compacted hard as a rock?

I had been told that a silt soil, when professionally compacted (from all the laboratory essays to the compaction with a vibratory roller), ends hard as a rock, and when hit with a metal bar it makes ...
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3answers
684 views

Retaining Wall: Saturated Soil & Hydrostatic Pressure

I understand that Hydrostatic pressure and Soil pressure exist concurrently. I'm curious how these separate loads interact with each other. Full disclaimer: I am not an engineer nor do I pretend to ...
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1answer
73 views

What is a safe soil load to avoid settlement?

For residential design, looking at IBC 2012 Table 1806.2 it seems a safe soil load to design for is 1500 psf if you want to save time and cost isn't yet an issue. (assuming you're not building on a ...
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112 views

Bored Pile construction Procedures When having Water in the ground

I know the normal process of how bored piles are normally constructed, but I need to know in case we have a water table at 1.5 m under the surface level and the pile must be at a depth of 25 m. How do ...
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1answer
82 views

Is there a torsion test in rocks?

If so, what would it be its official name? it might have another name than Torsion test because I googled it and nothing was found. pdta: I know there is a torsion test for metals , but that is not ...
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1answer
30 views

Load conversion for geotech problem

This is a basic question but for some reason it has me stumped. I am modeling a continuous load on a soil layer on a commercial FEA package. This is a plane strain problem where the layer is modelled ...
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1answer
561 views

To Which distance Punching Shear Reinforcement is placed in Mat Foundation?

As I know, a thinner mat may be possible by providing a nominal amount of vertical reinforcement as compared to a mat without vertical reinforcement, the vertical reinforcement is used to resist ...
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2answers
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What is the physical meaning of Cumulative Passing% in Grain Size distribution?

When preforming a grain size distribution on a sample of Soil using Mechanical Sieves (e.g. Sieve #4 and sieve #10 and sieve #40) one of the necessary calculation need for drawing the particle size ...
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1answer
74 views

Equipment or method for borehole

I am working at a construction site and came accross this issue. a borehole needs to be expanded in length inside a container-office. Working space is as little as 6m x 3m (19ft by 9.5ft). Height of ...
2
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1answer
597 views

Postion of overturning moment for retaining wall

I sometimes design my retaining walls with longer toes and heels, this is because in my FEA program, when I pull my footing under my wall towards the toe, I get lower pressures on my soil (springs) ...
3
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3answers
112 views

Base or foundation?

Please help, what is the correct term for: The bottom/foot part of building or structure which carries loads from the building/structure and transfers the loads to the soil/earth/ground beneath it? ...
4
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1answer
486 views

Difference between 'plastic yielding' , 'plastic yield strength', plastic strength' and 'plastic stress'?

I am going through a literature where these terms are regularly used and I am confused are they different and if yes then what does each term mean? I also want to know relation of plastic strength of ...
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2answers
14k views

Active vs passive earth pressure

Could anyone please explain what is the difference between active and passive earth pressure when we talk about weight retaining walls. Both are lateral pressure exerted by the soil on a retaining ...
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0answers
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Penetration rate for miniature cone

Is there any recommended/suggested/required penetration rate for a miniature cone penetrometer? A 20mm/s is for a standard size of cone penetrometer, what about for miniature one?
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2answers
2k views

How does excess water makes soil compaction more difficult?

I understand how water content helps compaction, by being kind of a lubricant between the soil particles, that helps them slide into position. But I don´t really understand how it starts affecting ...
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29 views

Moisture Corrections on MOD AASHTO?

I work in a lab and the people has learned a method of correcting the Moisture Percentage to fit the graph, I haven't seen this in any of the books i have on road works. is this a legitimate or is ...
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2answers
840 views

Connections between RC retaining walls and sheet pile retaining walls

I'm working on a flood defence scheme in which a section of RC flood wall becomes sheet piles. The reasons for this aren't important, but the solution isn't to simply make all walls one or the other. ...
4
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1answer
499 views

How can the bearing capacity of an existing tarmac road be determined?

From a typical ground investigation borehole log the tarmac thickness is recorded but no tests have been carried out on the road surfacing or formation level. I'm after an approximate bearing capacity ...
3
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1answer
130 views

Is a particular bund/embankment geometry more stable than others?

I am interested in structural stability of earthen bunds. They are susceptible to being eroded by water. Let us assume I have a rice field that is surrounded on all four sides by earthen bunds. I ...
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4answers
8k views

What is the difference between “Crushed Stone” and “Crushed Gravel” aggregate?

Crushing Question While reading a material specification for crushed aggregate, the text mentions both "crushed stone" and "crushed gravel" are acceptable. These materials sound very similar, but ...
7
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2answers
77 views

Should P-Δ effect be considered for struts of a braced excavation?

Building codes such as BS5950 provide clear guidelines on how to consider P-Δ effect due to sway of a vertically loaded portal frame or single storey building, causing additional moment in the columns....
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1answer
1k views

Why does the Channel Tunnel enter the ground around 10 km from the coast?

I know that digging tunnels is always much more costly than building ways or train above ground. Why doesn't the Channel Tunnel start around the coastline? Why does it have an around 10 km long ...
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0answers
32 views

In what ways could coastal cities like New York/Boston/Miami mitigate future sea level rises and maintain current dry land area? [closed]

We've all read articles on rising sea levels and the impact it will have on coastal cities in the coming decades. There are even maps that illustrate how varying levels of rising seas will impact the ...
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1answer
136 views

What are the risks and possible mitigations of installing ground anchors under spread footings?

I am installing a retaining wall in front of an existing bridge abutment that is supported by a spread footing. Because of the geometry of the site, ground anchors are required to help support the ...
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2answers
906 views

How can double I-section walers be spliced to ensure effective moment transfer?

I notice that quite a number of deep excavation projects adopt double I-section walers to form a box beam since standard rectangular hollow sections don't come with such large sizes. The I-sections ...
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2answers
6k views

Optimum Moisture Content and Maximum Dry Unit Weight

Anyone know how to solve for the OMC and MDD using mathematical solution? The book says its OMC is 13% and MDD of 2020. I tried using $a+bx+cx^3$ and getting its maxima but its far from 13%
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1answer
404 views

How is drilled shaft lateral resistance calculated using LPile?

The AASHTO LRFD Bridge Specification, Section 10.5.3.3 says "shaft lateral resistance" should be checked at the strength limit state (i.e. factored loads). How is shaft lateral resistance determined ...
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1answer
144 views

What drives improvements in seismic safety?

I get the impression that a lot of old buildings fail to meet modern earthquake safety norms, and need to be rebuilt or retrofitted. But what has changed in the last few decades that would make a ...
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3answers
625 views

How are earthfills not eroded before they are overgrown with grass?

Almost every railroad and vehicle road landfill has its slopes overgrown with grass which is quite good at preventing erosion. However it takes some time (a year or more) for the grass to grow and ...
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1answer
100 views

Dynamic Cone Penetrometer (DCP) results and correlation

I have been reading about DCP and watched a video of how it is done (the video is not in English). But there are some things that are still unclear and I would greatly appreciate some help and ...
3
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1answer
729 views

Classification of aggregates

I have this aggregate gradation curve in hand, how can I say whether its gap, well or uniformly graded?
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1answer
674 views

How to determine the lateral earth pressure in a double-walled cofferdam?

The design of a retaining wall commonly involves determining the lateral earth pressure using either Rankine theory or Coulomb theory. Both theories involve mobilising the shear resistance of a ...
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2answers
2k views

Why are earthfills fully covered in concrete where they join bridges?

Here's how a typical earthfill carrying a roadway joins a typical bridge Parts of the earthfill slopes are greenish - that's grass - and parts are whitish - that's concrete. The earthfill slope is ...
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1answer
2k views

Stress Bulbs for strip “continuous” footings [closed]

How can I plot such a graph with Excel or Matlab by a uniform load q, and how can I see where the stress becomes 0.1q? The loaded area and the equation is on the picture shown below, equation is ...
12
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2answers
1k views

Why do earth cuts sometimes have steps on their walls

A neat image from Wikipedia: There're clearly visible steps on the cut wall. This makes the cut wider at the top and so requires more work so those steps have some serious reason behind them. What's ...
8
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1answer
158 views

Localized stabilisation of Lunar lava tubes

A study from Purdue University suggests the Moon contains a number of wide underground lava tubes, up to 5000 m wide and about 1500 m high, in which subterranean cities could be constructed. Such ...
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2answers
142 views

How are the structural properties of intentionally frozen soil determined?

Soil freezes naturally all of the time. It is at this point that dirt work usually stops. Occasionally soil is intentionally frozen to improve its structural properties. This process has been used ...
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1answer
573 views

How do engineers deal with sinkholes?

Sinkholes have been known to occur in the middle of cities or other locations where they affect buildings: Some areas are more prone to sinkholes than other areas because of the presence of old mines ...